A FINITE ELEMENT TIME DOMAIN MODAL FORMULATION FOR LARGE AMPLITUDE FREE VIBRATIONS OF BEAMS AND PLATES

Abstract A finite element time domain modal fomulation is presented for the large amplitude free vibration of plates. The procedure of deriving the non-linear modal equations of motion is simple and general. Accurate frequency—maximum deflection relations can be obtained for the fundamental and higher non-linear modes. The percentage of participation from each linear mode determines the number of modes to be included for accurate frequency results. Numerical examples on beams and square plates are given and compared with classical continuum analytical solutions. A plate of complex planform and boundary conditions is also given to show the versatility of the presented modal formulation.